It is known in the art to prepare photosensitive silver halide grains in the presence of ammonia. For example, on page 61 of Photographic Emulsion Chemistry, G. F. Duffin, The Focal Press, New York, 1966, it is stated that ammonia is generally introduced into the silver halide precipitation procedure either in the silver solution or alternatively in the halide gelatin solution and/or in the added halide in a double jet procedure. Examples of such procedures also appear in the patent art.
U.S. Pat. No. 2,005,837 discloses a method in which comprises introducing into an ammoniacal silver nitrate solution, a solution of gelatin, ammonium bromide and potassium iodide. Subsequent to the initial addition, after about a half an hour elapsed time, is added an additional solution of ammonium bromide and potassium iodide.
U.S. Pat. No. 2,184,013 is directed to the method which comprises mixing solutions of potassium bromide, potassium iodide, gelatin and ammonium hydroxide with an ammoniacal silver nitrate solution.
U.S. Pat. No. 2,576,850 describes the process of simultaneously adding to a solution of completely hydrolyzed ethylene/vinylacetate, a first solution of ammoniacal silver nitrate containing sodium dodecyl sulfate and a second solution of ammonium bromide, potassium iodide and sodium dodecyl sulfate.
U.S. Pat. No. 3,598,593 discloses the preparation of ammoniacal silver halide emulsions employing a double jet procedure wherein ammonium bromide and silver nitrate are simultaneously jetted into a solution of potassium bromide and gelatin.
U.S. Pat. No. 3,647,458 is directed to a method for the preparation of direct positive emulsions which comprises the steps of adding to a solution of gelatin, ammonium bromide, potassium iodide and glycol aldehyde a first solution of an ammoniacal silver nitrate and then 30 minutes subsequent to said addition, adding a solution of ammonium bromide and potassium iodide.